A power circuit for a portable device or the like, for example, a DC-DC converter, supplies a power-supply voltage desired for each IC from an input voltage. With respect to power obtained from a battery cell or a battery, the DC-DC converter supplies an adequate power source so as to satisfy a power-supply voltage and an allowable current that are desired for each IC. The DC-DC converter is used for a wireless communication terminal, a tablet terminal, or the like.
A Related technique is disclosed in Japanese Laid-open Patent Publication No. 2006-304512, Japanese Laid-open Patent Publication No. 2009-159703, Japanese Laid-open Patent Publication No. 2005-192312, Japanese Examined Patent Application Publication No. 7-10043, or Japanese Laid-open Patent Publication No. 2005-160254.